1. Technical Field
Exemplary embodiments of the invention relate to fluid systems. More particularly, exemplary embodiments of the invention relate to torsionally controlled swivel joints.
2. The Relevant Technology
In many fluid systems, fluids are transferred from one reservoir to another. For instance, in the oil and gas industry, fluids are transferred from storage tanks to transport vehicles (e.g., tank trucks, railroad cars, ships, etc.) so that the fluids may be transported to various destinations. To transfer the fluid from the storage tank to the transport vehicles, the fluids are pumped through a loader arm.
A first end of the loader arm is connected to a riser or stand pipe. The stand pipe is in fluid communication with the storage tank so that the fluid in the storage tank may be pumped from the storage tank and into the loader arm. The stand pipe typically provides a strong platform upon which the loader arm can be mounted.
To facilitate connection of a second end of the loader arm to the transport vehicle, the first end of the loader arm may be connected to the stand pipe with a swivel joint. The swivel joint may allow the loader arm to rotate in one or more directions so that the loader arm may be repositioned to enable the second end of the loader arm to be connected to the transport vehicle.
Due to the weight of the loader arm and the fluids pumped therethrough, mechanisms have been developed to counterbalance the rotational forces resulting from this weight. Counterbalancing the rotational forces reduces the level of effort required of an operator to manipulate the loader arm and increases the safety of these systems. Such counterbalancing mechanisms have included external counterbalancing weights, hydraulic cylinders, spring and lever arm assemblies, pulley and cable systems, and the like. Such systems include many external parts that are not only expensive, but which also get in the operator's way and sometimes cause physical injury to the operators as well as damage to the equipment itself.
In other cases, internal counterbalancing mechanisms have been used. For instance, torsion springs have been disposed with the swivel joints to counterbalance and support the weight of the loader arm and fluid therein. Although these internal mechanisms counterbalance the weight of the loader arms and fluid, they make the swivel joints difficult to assemble, disassemble, and service. For instance, during assembly of the swivel joint, the torsion spring is disposed within mating halves of the joint. The joint is then placed in a large vice to compress the mating halves together to align bearing races in each half so that bearings may be inserted therein. Likewise, when worn bearings need to be replaced, the swivel joint must be removed from the stand pipe and loader arm, placed in the large vice, and compressed to allow for the bearings to be removed. When the mating halves and the torsion spring are assembled, the swivel joint can be quite heavy and difficult to move, thus making it difficult to move the swivel joint to and from the vice when the joint needs to be compressed.
Accordingly, what is desired is a relatively low-cost swivel joint that can counterbalance the weight of a loader arm and any fluid therein. It is also desired to provide a torsionally controlled swivel joint that allows for ready assembly and maintenance.